1. Field of the Invention
The present invention relates to a press-die and a press-working method, for example, for processing a plate material to be a body panel of an automobile or the like.
2. Background Art
Conventionally, when a body panel of a vehicle is formed from a steel plate, a peripheral edge portion of the steel plate is previously pressed by a blank holder, and a press-die is then moved forward and backward to carry out the press-working.
By a press-working apparatus having the press-die, a deep drawing shape such as a small round shape may be formed depending on a portion required for the body panel in some cases. However, there is a fear that a crack or a wrinkle might be generated when the deep drawing shape is formed from a thin steel plate.
In recent years, therefore, there has been known a press-working apparatus capable of avoiding a generation of the crack or the wrinkle.
As shown in FIGS. 7A and 7B, in a press-working apparatus 1, an upper die 3 is attached to an upper bolster 2 capable of enabling a stroke in a vertical direction. A lower die 5 is attached to a lower bolster 4 disposed below the upper bolster 2. The upper die 3 and the lower die 5 are disposed opposite to each other. Moreover, a forming aiding member 7 to be controlled in forward and backward movements by driving means 6 is provided in the upper die 3 and can independently carry out a stroke displacement with respect to the upper die 3. Furthermore, a static die 8 for performing forming together with the forming aiding member 7 is fixed to a side part of the lower die 5 which faces the forming aiding member 7. In addition, a blank holder 10 for holding a peripheral edge portion of a blank 9 is provided on a side of the static die 8.
As shown in FIG. 7A, in a preparing state in which the blank 9 taking a shape of a thin plate is mounted between the upper die 3 and the lower die 5 and the forming aiding member 7 is slightly protruded from a lower side of the upper die 3, the upper die 3 is moved downward to interpose the peripheral edge portion of the blank 9 between the upper die 3 and the blank holder 10. When the upper die 3 is further moved downward, the blank 9 is interposed between the forming aiding member 7 and the static die 8 so that a deep drawing shape is previously formed. Finally, a residual part in the blank 9 is formed by the upper die 3 and the lower die 5 as shown in FIG. 7B.
Thus, a product can be obtained (for example, see Patent Document 1).
Patent Document 1: JP-B2-3720216
In the prior art according to the Patent Document 1, however, in some cases in which the forming aiding member 7 comes in contact with the blank 9 earlier than the static die 8 to start a processing operation, a crack or a wrinkle is generated in the blank 9, for example. When the blank 9 is formed by the upper die 3 and the forming aiding member 7, moreover, there is a fear that a linear breakage might be generated in a portion to be a boundary between the upper die 3 and the forming aiding member 7 in the product.